Aminoglycosides are an important group of antibiotics of which the commercial members are prepared by fermentation methods. Many aminoglycosides have as part of their structure the pseudodisaccharide neamine which has the following structure: ##STR1## The systematic name is 2-deoxy-4-O-(2,6-diamino-2,6-dideoxy-.alpha.-D-glucopyranosyl)-D-streptami ne. Compounds in which the neamine structure has been modified are known in nature. These modifications are limited to absence of the 3'-hydroxy, the 4'-hydroxy or both the 3'- and 4'-hydroxy groups. Tobramycin, 4'deoxybutrisin A and B, and gentamicin are examples of aminoglycosides containing these modified neamines. Antibiotics containing neamines with substituents other than hydrogen or hydroxy at the 3' or 4' positions have not been reported either from fermentation or chemical modification methods.
Aminoglycosides also exist in nature as pseudotrisaccharides. For example, kanamycin are known antibiotics which are described in the Merck Index, 8th ed., pp. 597-598. Kanamycin B is a compound with the following structure: ##STR2## Kanamycins lacking the 3' and 4'-hydroxy groups are also known; however, kanamycins with sulfur substituents at the 3' or 4' positions are not known.